496 SiLBERGERG : STIMULATION OF STORAGE TISSUES 



No mei'istem. 



N/8. — A number of meristematic cells but not so many as in 

 the control. 



After ten days : 



Control. — A great deal of meristem close under the dried 

 exterior. 



N/4. — A good deal of meristem but not so much or so close 

 to the exterior as In the control. 



N/8. — Nearly as much as in the control. Also close to the 

 exterior. 



After twenty-one days : 

 Control. — A very thick layer of meristem. 

 N/4. — A great deal of meristem but not so much as in the 

 control. 



N/8. — Layer of meristem varies in thickness. Sometimes 

 about the same as in the specimen poisoned with N/4 ZnSO^ and 

 sometimes nearly as thick as in the control. 



Experiment III. Tenth- and twelfth-normal solutions of zinc 



sulphate were used. 

 After six days : 



Control. — One row of cells meristematic. 

 N/io. — Almost the same as in the control. 

 N/12. — More meristem than in the control. 

 After fourteen days : 



Control. — Outer meristematic cells dried and new layer form- 

 ing within. 



N/ 10. — About the same as in the control. 



N/12. — Much heavier meristematic layer than in the control, 

 (See figure 4.) 



Experiment IV. Twelfth- and fourteenth-normal solutions 

 were used. 



After five days ; 



Control. — Fairly thick layer of meristem. 

 N/12, — A little more meristem than in the control 

 N/ 14. — More meristem than in the control — about the same 

 as in the specimen stimulated with N/12 ZnSO^. 

 After twelve days : 

 Control. — Heavy layer of meristem. 



